There are many bacterial organisms that can invade the digestive system of cats, leading to signs of diarrhea, vomiting, gas, abdominal pain, and fever among other symptoms.

Let’s take a brief look at four of these infections and the bacteria that cause them.

Salmonellosis

Many species of Salmonella bacteria are capable of producing disease. They can infect mammals, birds, reptiles, and even insects! Salmonellosis in cats is usually transmitted through the fecal-oral route by eating contaminated food or water, raw or undercooked meats or poultry, or eating infected prey such as songbirds. Clinical signs begin to appear in three to five days and include the sudden onset of watery diarrhea containing blood or mucus, vomiting, abdominal pain, or gas.

Other times infected cats may develop chronic diarrhea, or they can even be asymptomatic (without clinical signs). If the bacteria leave the digestive tract through the intestinal wall and get into the bloodstream (septicemia) this can be life threatening. Cats can become very sick with high fever, severe dehydration, weakness, sometimes a dangerously low temperature, or shock.

Salmonellosis is most common in young cats or those that are stressed, debilitated, immunocompromised, in crowded conditions, or have other diseases.

The infection is diagnosed by fecal culture, or by blood culture if septicemia is present. A single negative culture may not rule out the disease.

Salmonellosis is treated with supportive care, fluids for dehydration, and antibiotics if the infection is severe. Mild cases don’t always need treatment with antibiotics and using them can cause resistant strains to develop, or can produce a carrier state. A carrier cat is an animal that has the bacteria in his body without showing symptoms, but is able to shed bacteria and contaminate the environment.

Salmonellosis is a zoonotic (shared between animals and people) disease, so owners must be very careful when treating and handling sick cats. Cleanliness and proper hygiene are essential to prevent human infection. Cats can shed the bacteria for 6 weeks or longer if a carrier state exists. The bacteria live for a long time in the environment and often resist common disinfectants, so re-infection is possible if thorough hygiene measures are not carried out.

Campylobacteriosis

Campylobacteriosis is a disease caused by Campylobacter jejuni bacteria. Campylobacter jejuni are small, curved bacteria that have a “seagull-shape” when viewed under the microscope. The disease is most often seen in cats younger than 6 months, shelter cats, or immunocompromised cats. The bacteria can also be found in healthy cats showing no symptoms. Cats may develop severe disease for three to seven days, with diarrhea and decreased appetite. Diarrhea may or may not contain blood or mucus. The infection is transmitted through the fecal-oral route; cats ingest contaminated water or food, raw or undercooked meats and poultry, raw milk, or prey. Wild birds can contaminate water sources.

Some cats may be asymptomatic and can shed the bacteria in feces for a long time, contaminating the environment. This condition may be diagnosed by finding the bacteria in a specimen taken from the rectum, or by fecal culture, although false negatives are possible.

Treatment usually consists of supportive care, fluid therapy, and if severe, antibiotic therapy—based on culture and sensitivity results. Campylobacteriosis is also a zoonotic disease and is a leading cause of diarrhea in people. Infected cats are a source of human infection, however, the most common cause in people is food poisoning from eating uncooked or undercooked meats and poultry (especially chicken), or unpasteurized milk.

Clostridiosis

Spore-forming bacteria called Clostridium perfringens cause these infections. These bacteria can be part of the normal gut bacteria, but certain animals may be predisposed to disease-causing infection. Clostridium produce toxins in the digestive system that can cause sudden watery diarrhea that may contain blood or mucus, or alternatively, the bacteria might cause a chronic, intermittent diarrhea.

Sometimes your veterinarian can diagnose infection by finding large numbers of “safety-pin” shaped bacteria during a special microscopic fecal examination. Fecal cultures are also used for diagnosis. Treatment consists of antibiotics, and feeding a diet high in fiber. As for other infections, severe cases may need supportive care and fluid therapy.

Helicobacter

There are many species of Helicobacter. These are helical (spiral) bacteria that live in the stomach of many animal species including cats, dogs, humans, cheetahs, ferrets, and nonhuman primates. Helicobacter survive in the deeper stomach layers, well protected from the acidic environment. The prevalence in cats is high, but many cats have no clinical signs. However, Helicobacter bacteria may cause chronic vomiting, gastritis (inflammation of the stomach), abdominal pain, decreased appetite, and weight loss. The mode of transmission is uncertain but it is suspected to be the fecal-oral and/or the oral-oral route. It is also the subject of ongoing research whether infection predisposes cats to other diseases such as inflammatory bowel disease, food allergies, ulcers, or stomach cancer.

Diagnosis is by stomach biopsy, with special tests performed on the biopsy sample.

Treatment consists of administration of two different antibiotics and an antacid medication. At this time it is unknown if helicobacter infections are zoonotic, though suspicion is strong. The disease has been associated with peptic ulcers and stomach cancer in people. More research needs to be conducted on helicobacter infections in cats.

If your cat experiences signs of digestive system infections, it is important to follow up promptly with your veterinarian. Most intestine and stomach infections produce similar signs but the treatments are quite specific to the agent involved. Only testing will provide a definite diagnosis.

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